NEWS

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xyt 0.1.0 (2026-10-05)

First release. xyt lifts the extract(<read function>, <data.frame>) machinery out of raadtools, rewrites it against terra, and gives it a test suite that runs with no data behind it.

• New extract_xyt(read, xyt, ...) extracts values from a raster time series at points that each carry their own date-time. The series is described by a reader function rather than held in memory, so only the slices some point needs are read, and each of those is read exactly once, in catalogue order, whatever order the rows arrive in.
• The reader contract is two calls: read(returnfiles = TRUE, ...) returns a catalogue data.frame with a date column, and read(date, inputfiles = files, ...) returns a single-layer SpatRaster. raadtools readers satisfy it unchanged.
• New xyt_reader_check() runs those calls in the order extract_xyt() will make them and reports PASS/FAIL for each step of the contract.
• New xyt_source(slice, catalogue) builds a reader from two ordinary functions, so the returnfiles switch never has to be written by hand. A catalogue given as a function is called once, on first use, and reused for the life of the source. Sources have a print() method.
• extract_xyt(files = ) accepts a pre-built catalogue, in which case the returnfiles call is never made and the reader only has to read slices.
• New synthetic_reader() and synthetic_value() provide a series with no files behind it, with a closed-form value at any (x, y, t), so tests and examples run anywhere terra is installed.
• when = c("nearest", "previous") makes the time-matching rule explicit. raadtools documented ctstime = FALSE as nearest-in-time but implemented it with findInterval(), i.e. the previous slice. "nearest" is the default and matches the documentation; "previous" reproduces the raadtools numbers.
• ctstime = TRUE interpolates linearly between the two slices that bracket each point; method = "bilinear" interpolates in space as well.
• fact aggregates each slice before extraction, and crs sets the coordinate system the input points are in (default "EPSG:4326"); points are projected to the raster's CRS as needed.
• Points beyond the collection in time return NA with a warning rather than stopping the call. tolerance sets how far is too far, defaulting to 1.5 times the spacing of the series.
• ... is passed to the reader only. In raadtools it also went to extract(), which was the source of the xylim argument ignored and inputfiles argument ignored warnings. Extraction is controlled by named arguments.
• Character times are parsed one element at a time, so a track mixing whole days and date-times no longer has its times of day silently dropped by as.POSIXct() picking one format from the first element.
• Slice reads can run in parallel on mirai daemons. If mirai::daemons() are running, extract_xyt() uses them without being told to; map takes any function of (X, FUN), so map = lapply forces serial reads and any other mapper can be dropped in. New xyt_map_mirai() is the mapper used. The first slice is always read in the calling session, so it supplies the target CRS for every other task and a failing reader fails once rather than once per daemon.
• When mori is installed and daemons are running, the catalogue is placed in shared memory with mori::share() rather than serialised into every task (about 2.7 MB down to 284 bytes per task on a 16,000-row OISST catalogue, roughly halving wall time on six daemons). share = TRUE insists, share = FALSE refuses, and with no mori installed nothing changes.
• No S4. raadtools registered this as a method on raster's extract generic, which welded it to raster; extract_xyt() is a plain function with terra as the only hard dependency. mirai, mori and testthat are in Suggests.
• dev/bench-mirai.R benchmarks serial against daemon reads for a given collection and reports the serialised size of the catalogue payload.